There are some HDT tweaks a-brewin'. I'll let Ziggy or Steve give the full details when they are ready. In the meantime, here is one that you can easily do separate from the others. I got this from Ziggy...

Wrap the driver phase plug barrel - the sides of the socket not the front - with felt. From the tip to 1/2" back towards the voice coil. Meaning a strip of felt 1/2" wide and length equivelent to the circumference of the phase plug. The felt should be thin, similar to that covering the back of the driver magnet. This felt with self-adhesive backing can be had from Michaels or other craft mart.

Ziggy or Steve, When are you guys going to publish the HDT tweaks?Steve told me that the "stuffing" changes could be applied first, without applying the other changes, which I understand require some manufactured parts. Well, not really stuffing but inserting foam (I think it was) in specific amounts and locations.

I'd like to apply the first two tweaks to improve things while waiting for the others. Namely:

I applied the felt tweak to a set of the drivers. I also applied a tweak learned from John Wyckoff (Hammer Dynamics). That of painting a thin coat of silicon calk to the front edge of the whizzer cone. Don't glop in on (thick) or you may add some significant mass to the cone, negatively affecting it's sound...

The white ring in the above pic is white silicon glue applied to the whizzer cone. The pair I used to have some years ago looked like this. On the FE206 drivers I used black silicon (Home Depot) so it's not as visible.

Both tweaks have smoothed out the treble, though it may be more due to the felt than the siliconing the whizzer.

Still, I wish the bass had more meat. Hopefully, the other tweaks will help in this regards WHEN they come out .... Ziggy? ;)

For sure, I'm waiting for final judgement until after my TABOO arrives and is fully broken in. But right now I'm using a Panasonic home theater reciever - which actually sounds better than one might think. It uses the Tripath digital amp chips and is nice value considering it's low cost, sound, and features.The Panny has around 60 watts per channel, so while I was expecting it to sound bright and not image as well as a low powered tube amp, I was expecting the bass to be higher in volume (not necessarily speed and quality).

Also, since I have two sets of FE206E-M drivers, I can play with the tweaks on one driver and make comparisons (which I haven't done yet), and also don't have the fear of ruining my speakers.

btw, I have been told the other tweaks won't be released until the newly designed passive radiators come out - hopefully soon.Apparently the new cabinet tweaks/mods utilized a lengthening of the inside ports along with new passive radiators. You can add the port lengtheners (just PVC coupler and extra pipe) by reaching into the cabinet through the PR holes, so not a major deal. The cost of the new PR's will reportedly be very low, so for those thinking of buying an HDT/kit, there's no point in delaying the purchase while waiting for this tweak to come out. Also, Steve said he's not sure yet if this mod will actually go into production - perhaps just left to the DIY'ers.

There was also some mention of a highly modified version of the FE206E driver which has some elaborate/difficult-to-apply cone coating. I'm not sure when or if this mod will make it to production.

This is all I know about the tweaks - and that they are supposed to make the HDT sound better. Looking forward to more of Steve's never-ending pursuits of perfection ;D

Brad, Do you know if the new passives will require any change to the cut-outs in the sides? I am planning on glueing up my cabinets this week and have the cut- outs already routed as specified in the plans. I would like to modify these now rather than after it is glued together.I probably should e-mail Steve directly and force him to give me answers I also need to know about the port changes. I can easily replace the pvc ports now, before glue up.Thanks for the heads up

Steve said the "tweaks" will not require any cabinet mods. So obviously the PR's will fit in the same holes. The port mods can be easily made by reaching into the cab's through the PR holes and adding a length of pipe via a PVC coupler and glue. The port mods and new PR's work only together, so it doesn't make sense to use the new port length without the new PR's. Doing this would probably degrade the sound - perhaps creating some response hump.

I don't recommend calling Steve about this, since this will waist his time explaining to multiple people about this "pre-realease information" that he already explained to me. The final details will come out eventually. Now, if you want to ask questions here on the forum to him and/or Ziggy, and express you interest in these mods, it might help push Steve into getting the new PR's done sooner rather than later :D

Brad,I sent an e-mail to Steve. I agree that calling would not be a good idea. Hopefully he will post the tweaks soon. If I knew that the new passives would not be expensive I could move forward with confidence and not worry about having to punch out and replace them. I certainly do not want to pay $60 to make a tweak if I can hold off for say another week. Maybe if I knew when he was going to release the tweaks I could better decide. ???

Brad, is your passives kit just the foam surrounds or are they glued up assemblies? I may be interested in purchasing them from you. I bought the $100 HDT kit and it just had the surrounds. I bought the suggested craft foam and felt and plan to glue them to cardboard and then the surrounds.

I think I may go ahead and finish the cabinets and wait for others to comment on the new passives and ports. ???

What are you planning to do with your first set of 206 drivers?Were the HDTs that you bought made by Ziggy or were they homebuilts and how do they sound?Lots of questions.John

For anyone who has performed the driver socket mod (installed the phase plug) themselves, I have found on the two Decware-made FE206EM drivers that I have that the 1" socket sounds better than the 15/16" socket. To my ears, the treble sounds more extended, but smoother with less brightness. Perhaps a flatter response? It's not a huge difference, but a clearly audible one.

Of course there is VERY little tolerance between the 1" socket and the voice coil. I would imagine this is a difficult thing to DIY without screwing up the driver.

Caveat: the driver with the 15/16" socket was in my used pair of HDT's so I don't know how many hours are on them and I suppose it's possible they are not fully broken in. I know my drivers with the 1" socket has had MANY hours on them.

I only heard that the new tweak (port length change + new passive radiators) are supposed to make it sound better. How better - I don't know. As I said before, they go hand in hand. You can't change the port length without also changing the passives (which aren't out yet).

Since the release of the HDT loudspeaker design in 2003 we have come up with what we feel is a substantial improvement in overall performance of the HDT loudspeakers. If you’ve researched the design you know it was originally developed as a two-way loudspeaker in 1996 using a conventional 8 inch driver and 1 inch tweeter. When the design was adapted for the Fostex FE206E driver in 2003, the tuning of the ports andpassives was raised to accommodate the higher fs. This allowed the cabinet and Fostex to work together and with the addition of our Phase Guide to the driver the end results were quite good.

We found while comparing the original 1996 speaker with the HDT that the higher tuning of the ports and passives reduced the fundamental operation of the multi-chamber design. In the original speaker there is no treatment inside the enclosure or any of it’s chambers yet it has the most liquid midrange you’ve ever heard. The Fostex based HDT on the other hand was more congested. It saw most of it’s loading from the primary chamber leaving the secondary and averaging chambers doing little work and hence emitting little energy. This prevents the speakers from doing as good a disappearing act as the original 1996 model.

Since the cone of the FE206E driver is so thin it is important when you build a pair of HDT speakers to know exactly how to treat it and with what. This paper will describe the proper procedure for treating the inside of the cabinet. It will then cover the optional alternate tuning that we suspect will be received as a significant improvement even though we can find nothing bad written about the 200 pair that have been built to date.

The alternate tuning is optional because many will be perfectly fine with the way they sound now. And it requires an additional modification to the drivers, new passive radiators and different length ports. The ports can be easily modified once the driver and both passives have been removed from the cabinet.

The alternate tuning when combined with the correct treatment of the inside of the enclosure will result in a significant increase in bass and extension of bass frequencies. It will remove the congested sound in the midrange and treble and activate the complex beauty of the enclosure design to make all the chambers work resulting in a head shaking disappearing act.

CABINET TREATMENTThe material used for all internal cabinet treatment is 1 inch thick egg crate foam like that used as mattress toppers. You can find it at Wal-Mart, Target, and most fabric stores. After you have removed the driver and both passives, or when you are building the cabinet new you should install this foam in specific places, cutting each piece for a snug fit.

Piece 1 is a 12x12 square that fits in the bottom of the averaging chamber. It can be installed though the square port in the lower rear of the cabinet or from the top through the transmission line.

Piece 2 is a 16x7 rectangle that fits on the rear panel behind each passive opposite the oval cut-outs. It should be pushed to the top of the chamber. You will have one of these pieces for each side of the enclosure.

Piece 3 is a triangle that fits in the top of the primary chamber above the driver.

Piece 4 is a 4 inch strip that mounts under Piece 3. It should be cut to a length to cover all three sides of the primary chamber.

Piece 5 is cut to match piece 4 and located just below the driver opening where as piece 4 is located just above the same opening. Piece 5 will also just cover the bottom of each oval cut-out so it should be notched so as not to obstruct the opening.

DRIVER MODIFICATIONThe driver should be returned to Decware for a special viceoelastic wax glaze on the cone which lowers Fs slightly and improves midrange.

PASSIVE RADIATOR REPLACEMENTThe passives should be replaced with the alternate design available from Decware.

PORT LENGTH MODIFICATIONFront port should be lengthened from 6 to 11inches and the side ports lengthened from 8 to 17 inches. Use PVC

The alternate tuning for the HDT loudspeakers will become standard in the Fall of 2005 after it is debuted at our October DecFest. A kit will be available that includes the following:

1. 6) 2 inch PVC port tubes with couplings for lengthening theports. This can be done once the passives and main driver have been removed without tools and is reversible.

2. 4) Alternate design passive radiators. These replace the original passives and are glued in just as they were. This mod is also of course reversible.

3. 12) pre-cut pieces of foam used for internal reflection control. Replaces felt previously used. This mod can remain even if the other mods are reversed.

The final stage will be having the drivers modified with gel wax to drop the fs and fully active the mods listed above. This mod is not reversible. You can either purchase a new pair of drivers from Decware with the gel wax mod, or send your original drivers in for upgrading.Prices for these mods will be listed on the Decware web site in theHDT pages when they become available.

FREQUENTLY ASKED QUESTIONS

Q) Can I ship my HDT’s back to Decware for these mods?A) No. Shipping these speaker cabinets back to Decware ensures a 70% chance they will be damaged or destroyed by UPS. It’s just not worth the risk. You can drive them to our cabinet facility in Mesa AZ or to our amplifier facility/home office in Peoria IL if you want. Bob or Steve will be happy to upgrade them. Upgrading them yourself is easier then it sounds. You can also consider having a friend come over to help you.

Q) Can I mod my HDTs without the updated passive radiators?A) The updated passives applied to the standard HDT’s without any of the other mods will not adversely effect performance or fidelity.

Q) Can I apply all of the mods but continue to use the originaldrivers?A) Yes. The sound of the original drivers will not suffer from the mods. The gel wax modified drivers will however take advantage of the mods to a far greater extent.

Q) Can I have my original HDT drivers modified with gel wax and forget the other mods.A) Yes. You will hear an improved midrange with slightly more bass and about 1 dB less overall efficiency. However, implementing the other mods will greatly enhance it’s sound by further improving the midrange, lowering the bass and significantly improving the imaging.

Q) Will the lower bass response and added weight take away from the speed of the bass — I really like the HDT bass the way it is.A) NO. It will be just as fast, but come off slightly warmer anddeeper.

CAUTION:

The HDT loudspeakers have a solid reputation among serious audiophiles in their standard configuration. If you own a pair and simply love the way they sound you should consider leaving them alone. The updates will add more weight and bass response which could tip the delicate balance you may have achieved with the rest of your system and room. We expect that in most cases the alternate tuning will be perceived as better but there will always be exceptions.

We have been field testing the alternate tuning all year with various HDT owners and the improvements so far have been 9 out of 10 thought it was an improvement. With that in mind,if you love the way your HDT’s sound now, there is a 10% chance they will sound worse after the mods.

Of course, the worst case scenerio would be you falling into that 10% in which case you could reverse the mods. If you purchased a second set of drivers with the gel wax and still have your original drivers, reversing the mod would be fairly painless.

Alright guys the ports have been modified and the foam is in place. They've been playing with the Zen for about an hour and I swear theyre imaging better and sounding more open. As for the bass, my square room and the current speaker placement make for muddy crappy bass from any speaker (but good imaging). I'm going to move them to another place where I know the bass is decent and possibly buy some rolls of fiberglass to use as a bass trap. As for now I can tell theres a little more bass extension. I'm going to drive them with a more powerful amp tomorrow; this is always fun. -Matt

Thank You Steve.I still have a couple of questions.... Do we still use the 1/2" felt behind the drivers like Ziggy suggested originally, or are these pieces of convoluted foam all we need? What about Poly-fill in the top of the chambers? Can the new passives be made by hand with the same surrounds you supplied in your kit? I have not glued these together yet and can wait if the info will be released soon. Sorry for all the questions, but an answer will help me decide which course to take.Thanks,John

If I remember correctly from my talk with Steve, the new passives are dual-articulating and/or dual-tuned. I don't think it's as simple as changing the mass of the PR. Of course, I've been wrong before

Question for Steve/Ziggy: Have you guys tried tuning the left and right side of the speaker differently? ie, different length port on the left/right sides, and perhaps keeping the original PR on the left and putting the new one on the right? Sorta same idea as offsetting a driver in a baffle to average out peaks in the response? Or perhaps this is un-necessary and/or would just screw up the tuning and sound?

I was just thinking this might be a happy medium for any in the mentioned 10% that like better the un-modified/stock version of the HDT.

[quote author=zinker link=1113323574/30#30 date=1117558859]Thank You Steve.I still have a couple of questions.... Do we still use the 1/2" felt behind the drivers like Ziggy suggested originally, or are these pieces of convoluted foam all we need? What about Poly-fill in the top of the chambers? Can the new passives be made by hand with the same surrounds you supplied in your kit? I have not glued these together yet and can wait if the info will be released soon. Sorry for all the questions, but an answer will help me decide which course to take.Thanks,John [/quote]

No, you do not need the felt. The foam replaces it.Poly-fill in the top chambers has also been replaced by foam.

The new passives start with the same surround which is glued to a 6 inch surround that is in turn glued to a 4.5 inch paper dome. The dome is supported by another specially shaped cap glued to the inside along with the appropriate weights.

[quote author=Falconer link=1113323574/15#29 date=1117540494]Perfect timing on the mods, I'm ready to cut and glue pvc into the port plate tonight (5-31-05). I'll have to check with Decware and see if the drivers shipped to me had the wax job. [/quote]

Unless I specifically say so over the phone prior to or after an order, the drivers will not be gel waxed but rather exactly as represented on the web site. I have waxed a few for people I've talked to about doing so, but otherwise my plans are to simply replace the current model with it when we start building the HDT's this way as standard.

At this point that will probably happen in October directly after the 2005 Zenfest here at Decware. The information and required parts are being made available now because we know many of you will jump on the mod and report the results. If they are all positive it will of course make the debut at the Zenfest something to look forward to. If the reports come back negative then we won't take it into production. That said, I'm betting my ear's reputation on an overwhelmingly positive report. I'd hate to have wasted my time and consider our customer's time to be equally valuable.

Thanks for the quick reply Steve.Since the new passives are a completely different animal, I think I will use the old ones for the time being. I will ,however, use the new foam interior scheme along with my non- modified drivers until I hear from others about thier experiences. This project has been in works for so long now and my amp is just sitting gathering dust. I MUST HAVE MUSIC NOW! I hope the new passives are not too expensive.John

Well I've been listening with my more powerful Peavey SS amp. The bass is certainly different. The cone motion is more regulated so the drivers dont move as much. I think the passives are activated more. I'm willing to try the new ones. So far so good. Also on certain songs an upper midrange peak is more noticable with the new tuning. I assume the new driver coating deals with this. And like I said, they do image better.

Do you have the first generation of the Fostex driver where the socket is painted black and bonded to the pole piece?I was wondering if you have applied any felt to the socket? Can a person do this without removing the bonded socket?

The HDT Alternate tuning kit is now available for those of you who have been following this forum.

It includes:

1) The additional port lengths and couplings used to lengthen the original ports.

2) The newly designed passive radiators

3) The pre-cut foam pieces that replace the felt and or polyfill.

The cost is $126.00 for the kit and it will do both speakers.

It can be ordered ONLY from our master catalog or by phone.

The gel wax treatment of the fostex drivers is optional. Those who wish to try it may send their drivers to DECWARE and I will personally modify them.

Cost to gel wax drivers that are sent in will be $50. for the pair.

IMPORTANT NOTICE:

1) There is nothing wrong with the original HDT speakers.2) These tweaks are not a FIX.3) These tweaks, also known as the Alternate Tuning, have been made available to forum members who like to modify things. They are not mentioned or listed anywhere in the HDT pages on the site.4) The Alternately tuned HDT's will be debuted at this years DECWARE ZEN FEST in October. Afterwards, the HDT pages on the site will be updated to reflect the changes and we will introduce these changes into production. At the same time the price of the HDT will increase slightly.

A while back I was speaking to Ziggy about these tweaks and he mentioned that the passive radiators would be "added" to the existing ones foam surround. He said removing the foam and glue from the wood is just too much work.

My question is how should I go about removing the old passives? Do I have to salvage anything? Or can I just cut those ones off and strip away all the foam and glue? I just don't want to fuck anything up.

BTW, Steve. Your focus on this part of your buisness is much appreciated and looking forward to my new "Sluts."

You don't need any of the old passives. If you take a hobby knife (X-acto) and just find the thru hole for the passives and cut the foam surround along the hole, it will leave whats glued to the cabinet in place. you'll then glue the new passive to the old (whats left of it) passive.

If you try to remove the passive and it tears the apart. it won't be smooth enough to adhire or seal with out removing it back down the the wood itself.

Brad,Sluts was the nickname given to the earliest designs of what is now the HDT cabinet. They named them "slut" cause just about anything (driver) you put in em sounded good! Did I get that right Bob?